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濒危植物疏花水柏枝残存种群数量及群落特征

Population and community characteristics of remnant populations of endangered Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang

  • 摘要: 为揭示濒危植物疏花水柏枝(Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang)残存种群的分布格局及群落结构特征,对三峡大坝下游长江流域疏花水柏枝残存种群的分布地(点军胭脂坝、董市江心岛和枝城官洲岛)开展了物种组成、数量、多样性、区系成分和生活型谱等研究。结果显示,疏花水柏枝残存种群分布地共有植物38科73属83种,群落类型为灌丛,灌木层优势种为疏花水柏枝和秋华柳(Salix variegata Franch.)。疏花水柏枝仅在夏季水淹、冬季露出区域呈团块状分布,为增长型种群类型,群落稳定性较差,点军胭脂坝约为222 300株,枝城官洲岛约为774 700株,董市江心岛约为197 400株。3个分布区物种丰富度指数(S)为10.5 ~ 11.5,多样性指数(H)为1.21 ~ 1.54,均匀度指数(E)为0.74 ~ 0.91,优势度指数(D)为0.53 ~ 0.69,表明物种多样性指数均较低。研究区植被符合我国亚热带地区植被区系成分,但生活型谱主要为地下芽植物和一年生种子植物,与热带亚热带沙漠气候植被类型相似。

     

    Abstract: To determine population number and community characteristics of remnant populations of endangered Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang, we investigated and analyzed the species composition, population number, species biodiversity, floristic composition, and life-form of M. laxiflora populations in the Yangtze River Basin downstream of the Three Gorges Dam (Dianjun, Zhicheng, and Dongshi islands). Results showed 83 species, 73 genera, and 38 families of plants in the distribution area of the remnant M. laxiflora populations. The shrub community was dominated by M. laxiflora and Salix variegate Franch. The M. laxiflora population was only distributed in clusters in the flooded areas in summer and exposed areas in winter, with poor community stability. The M. laxiflora population consisted of about 222 300 individuals in Dianjun island, 774 700 individuals in Zhicheng island, and 197 400 individuals in Dongshi island. For the three distribution areas, the species richness index was 10.5 – 11.5, Shannon-Wiener index was 1.21 – 1.54, Pielou index was 0.74 – 0.91, and Simpson index was 0.53 – 0.69, indicating that species biodiversity was low. The vegetation distribution areas were characterized as North Temperate and Pantropic, similar to the vegetation floristic composition of subtropical regions in China. However, life-forms were mainly geophytes and therophytes, similar to the tropical and subtropical desert climate vegetation type.

     

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